Magnetic Fields
Learn Magnetic Fields for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. A magnetic field is strongest at the poles, field lines run from north to south, and a compass shows the direction of the field.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
A magnetic field is the region around a magnet where a force acts on another magnet or on a magnetic material.
The field is strongest at the poles, and the strength decreases as the distance from the magnet increases. Field lines are drawn to show the field, and their spacing indicates its strength — closer lines mean a stronger field.
By convention, field lines always point from the north pole to the south pole of a magnet. A plotting compass can be used to map a field, because the compass needle aligns with the field direction at each point. The Earth itself has a magnetic field, which is evidence that its core is magnetic.
Revision notes
The field and its strength
A magnetic field is the region around a magnet where a force acts on another magnet or magnetic material.
The field is strongest at the poles. Its strength decreases with distance from the magnet.
Field lines
Field lines show the direction and strength of the field.
By convention they point from the north pole to the south pole. Closer lines mean a stronger field. Field lines never cross, because the field has only one direction at each point.
Plotting compasses and the Earth
A plotting compass needle aligns with the magnetic field at its position, so moving it around a magnet maps the field.
A compass needle points north because the Earth has its own magnetic field, which is evidence that the Earth's core is magnetic.
Key points
- A magnetic field is where a magnetic force acts.
- The field is strongest at the poles.
- Field strength decreases with distance.
- Field lines point from north to south.
- Closer field lines mean a stronger field.
- A compass needle aligns with the field.
Worked examples
Example 1
State the direction in which magnetic field lines point. [1 mark]
Model answer
From the north pole to the south pole of the magnet (1 mark).
Example 2
Describe how a plotting compass can be used to map the magnetic field around a bar magnet. [3 marks]
Model answer
Place the compass near the magnet and mark the direction the needle points (1 mark). Move the compass so its tail is at the previous mark and repeat (1 mark). Join the marks to trace out a field line, and repeat starting from different positions (1 mark).
Example 3
Explain what the evidence of a compass needle pointing north tells us about the Earth. [2 marks]
Model answer
The compass needle aligns with a magnetic field (1 mark), so the Earth must have its own magnetic field, which is evidence that its core is magnetic (1 mark).
Common mistakes
Drawing field lines from south to north.
By convention they point from north to south outside the magnet.
Drawing field lines that cross.
They never cross, because the field has one direction at each point.
Saying the field is uniform around a bar magnet.
It is strongest at the poles and weakens with distance.
Forgetting the Earth's field as evidence.
It is specifically required as evidence that the core is magnetic.
Exam tips
- Learn the north-to-south convention.
- Use line spacing to describe field strength.
- Describe the compass method as a sequence of steps.
- Mention the Earth's core when discussing compasses.
Key terms
- Magnetic field
- The region where a magnetic force acts.
- Field line
- A line showing the direction of the magnetic field.
- Plotting compass
- A small compass used to map a magnetic field.
- Uniform field
- A field of constant strength and direction.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.